Measuring Automatic Transmission Shift Performance

Results of a psychophysical experiment indicated that “jerk” (that is, rate of change of fore and aft acceleration) associated with the clutch-actuated gear ratio change in an automatic transmission correlated well with subjective evaluations of shift-feel. A portable device, the GMR Jerkmeter, was constructed to measure acceleration and jerk during on-the-road evaluations of transmission performance.

Techniques for using Jerkmeter data in automatic transmission fluid research and development projects are discussed. Examples are given of the use of Jerkmeter data to:

1. 1.
   Produce a detailed characterization of shift performance.
2. 2.
   Measure effect of fluid on shift performance.
3. 3.
   Study effect of changes in fluid characteristics with use.